Submitted to: Plant Biology
Publication Type: Other
Publication Acceptance Date: 8/20/2002
Publication Date: 2/20/2003
Citation: PLANT BIOLOGY 2002, ABSTRACTS OF NATIONAL MEETING OF THE AMERICAN SOCIETY OF PLANT BIOLOGISTS. ABSTRACT 535, P. 127.
Interpretive Summary: ABSTRACT ONLY
Technical Abstract: Plant disease is the most important problem for the US papaya industry and development of disease resistant papaya is critical for maintaining competitiveness of the industry. Our goal is to confirm that papaya has a systemic acquired resistance (SAR) response similar to other plants, and to develop the tools needed to monitor SAR in papaya engineered or treated to improve disease resistance. Previous work (ref) showed that Benzothiadiazole (BTH) treatment increased -glucanase and chitinase enzyme activities, and reduced disease symptoms of seedlings inoculated with Phytophthora palmivora. In arabidopsis, NPR1 plays an important role in signal transduction and activation of SAR. We now report cloning of an NPR1 homolog from papaya. It shares 71.04% and 66.84% amino acid similarity with rice and arabidopsis respectively. It also contains the ankyrin repeat region and a possible nuclear localization sequence, which are critical for NPR1 function in arabidopsis. Our work and the BTH study (ref) confirm that there is a SAR pathway in papaya, similar in at least some major aspects to that characterized in papaya. We are engineering papaya to overexpress NPR1 in order to improve broad-spectrum resistance. To analyze these transgenic lines, four PR-1 like genes were isolated from papaya. Steady state mRNA level for one of these (designated name?) increased more than 17 fold three days after BTH application to leaves. Steady state mRNA pools for the other three related genes did not increase in response to this treatment.